In the proposed phase II NIH STTR funding opportunity (PA-12-089), LodeSpin Labs (LSL) is developing a magnetic nanoparticle tracer for use in Magnetic Particle Imaging (MPI), a disruptive new medical imaging technology currently being developed as a safe, effective and quantitative alternative to existing cardiac imaging technologies like CT and MRI. MPI is a promising safer alternative to current CT angiography procedures; it uses safe magnetic fields (no ionizing radiation) and safe iron oxide nanoparticle tracers. Unlike MRI, it offers real-time imaging that is quantitative and has potential for sub-mm spatial resolution. MPI shows tremendous potential as a safe clinical imaging procedure for diagnosis and treatment of cardiovascular disease (#1 cause of deaths in the US), and opens doors to novel molecular imaging applications. However, it remains under development largely due to the unavailability of suitable tracers. While iron oxide nanoparticle tracers exist, having been developed for MRI as well as for iron replacement in CKD patients (Feraheme), LSL's tracer is the first, and only, tracer to be designed specifically for MPI. Furthermore, there is unanimous agreement in the industrial and academic research community developing MPI hardware that LSL tracers provide superior MPI imaging performance, which will enable MPI's clinical and commercial potential. Therefore, LSL has a significant opportunity to be the first provider of high-performing MPI tracers in the emerging pre-clinical MPI market and future clinical market. In Phase II, UW and LSL, in partnership with industrial giants Bruker BioSpin and Philips Medical Systems, will demonstrate real-time in vivo imaging in phantoms and live animals. LSL has further strengthened its team by including Dr. Steven Conolly, as an imaging scientist consultant, and Dr. Julian Simon, as a conjugation and medicinal chemistry consultant. LSL will also pursue pilot toxicology studies that will demonstrate tracer safety to future investors and enable joint ventures that will ultimately fund future regulatory studies. In Phase I our efforts to develop optimized tracers, and strategic partnerships with Philips Medical Systems (Limited Evaluation License) and Dr. Conolly's group at UC-Berkley (Material Transfer Agreement) have positioned the LSL team as pioneers in MPI tracer technology. There is unanimous agreement in the MPI community that LSL tracers outperform any iron oxide formulation currently in the market. Thus, we envision our tracers as truly enabling MPI in achieving its clinical and commercial potential. In Phase II, LSL's immediate goals are to demonstrate our tracer's superior performance in phantom and in vivo imaging, targeting sub-mm resolution (SA1) in both time- and frequency-domain image reconstruction methods, further enhance tracer performance to compete with current standards in x-ray CA procedures (SA2), and assess tracer safety in pilot toxicology studies in mice (SA3).